To create wiki-like functionality in you Drupal site, you can use the node_privacy_by_role module to enable everyone to edit any post of a particular content type.

1. Go into administer->modules and enable node_privacy_by_role.
2. Go the administer->settings->node_privacy_byrole page and enable it again using the button provided there.
3. Pick a content type you would like to enable all students to create and edit. If you do not plan on using it otherwise, you could use the page content type. Or you can create your own using flexinode.
4. Once you've decided on a content type, go to administer->access control and enable create and edit permissions for authenticated users for the content type you are using.
5. Go to administer->content->configure->content types. Select configure beside the content type you want to use.
6. Check authenticated user in the Default Edit Permissions area.
7. Leave the rest of the permissions unchecked; they will default to Drupal's normal behavior and how they have been configured in access control.
8. Create a post as the teacher. Then test it by editing it with a test user with only
   authenticated user permissions.

Optional: You can add more wiki-like functionality by enabling one of the following modules:

• wiki. This module enables the wiki style markup used by phpwiki. Once you enable the module, you must go to administer->input formats and create a wiki input format. Then configure it by adding the wikitext filter. Note: HTML will not work with wikitext pages.
• freelinking. Allows users to create CamelCase words with wiki functionality. Once you enable the module, set the defaults in administer->settings->freelinking. Then go to administer->input formats and configure each input format to use freelinking.